I'm in WI's camp on #40. People say 'Thank you' to show appreciation in many circumstances. Why not after sex? I don't see why it's different. (And Lou, I'm in no way attempting to invalidate your feelings.) I appreciate it when my wife rocks my world... therefore I say thank you.

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Put me on wheels and I'll turn tricks.

Clever? Nah, I ran out of that years ago. But if you find this, let me know, k?
"The road goes ever on..." ~ Tolkien

In memory of my friend skip...
Go then, there are other worlds than these